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Evaluation by MOIT of organic coating oxidation degree and degradation activity through thermogravimentry
Full text linkAbstract
The work relates to the study of the chemical and chemical-physical properties of artificially aged organic films, compared with those of the materials naturally aged (atmosphere exposure). The first objective of this study is the selection and validation of the most suitable instrumental methods to highlight the consequences of the degradative action due to photo-oxidation and/or weathering agents on protective coatings applied on wood substrates. With the MOIT term we indicated the Modified Oxidation Induction Time parameter that results from the instrumental analysis we used. It appears very sensible to property of materials and may be useful for the ageing assessment.
The technique involves a double weight loss analysis (TG) instead of the calorimetric analysis (as recommended in the standard method) on a sample of the film: the first being carried out in a nitrogen atmosphere and the second in an air atmosphere. In both cases the analysis is carried out under the same conditions, i.e. with a thermal profile which provides a heating ramp. At fixed time and temperature, the sample weights, determined under a nitrogen atmosphere, were subtracted from the sample weights homolog in air. The values obtained allow the determination of the "Δ", parameters and its evolution with temperature/time, from which it is possible to determine both the oxidation entity and the oxidation induction time. In this paper the authors illustrate the method referring to one acrylic resin used for coatin
Dangerous Substances from Industrial activities. Emission Estimation Method for Surface Water Concentration
No full textLow surface energy ceramic coatings
No full textThe research aims to coat aluminium surfaces with a film composed by hybrid organic-inorganic network and an high metal oxide content. The coating must have acceptable mechanical strength, release characteristic and must be produced through a not toxic, low temperature process. The study is connected to the industrial production of food (cookwares) and rotating cylinders for paper and plastic shaping. Thin hybrid coating films with a contact angle of 100-140° were obtained with the sol gel process using methyl and/or ethyl alkoxy silanes. They were obtained enclosing colloidal silica, α-Al2O3, and other fillers and using HNO3 as catalyst. Several different formulations has been used and the film are obtained after an appropriate thermal treatment. The choice of inorganic fillers appear critical. The increase of the colloidal silica (CS) increases the contact angle and the hardness but decreases the abrasion resistance. SEM analysis indicate that a thin homogeneous layer, free of inorganic fillers, is formed on the surface probably due to rheology behaviour of the colloidal mixture during the application. Due to the relevance of the CS content and of the other fillers on the surface performance, we needed to analyse the total fillers distribution along the thickness with GDOES instrument and SEM analysis.
The mechanical and morphological observations are discussed trying also to suggest some corrections in the ingredient content to optimise the formulation and the process parameters
SUPERHYDROPHOBIC COATINGS OBTAINED BY SELF-ASSEMBLED MOLECULES FOR LONG USE APPLICATIONS
No full textCeramic films on cast iron for high temperature treatments.
No full textThe research aims the deposition of low thickness ceramic films on the surface of cast iron forms that are used for recycled Pb moulding. The films will establish a thermal insulating coating to delate the metal solidification for a short time in order to complete an unforced mechanical scorification. Moreover the bars will assume a more uniform and market acceptable surface. The thermal conductivities of the cast iron (Meehanite HE type) and the ceramic material are 55 W/m°C and 2.2 W/m°C respectively. High temperature ceramic coating not suited to thin film production so the sol gel process seems appropriate to homogeneously apply a mixture of metal oxides at low temperature. To avoid the film shrinkage due to the phase evolution of the inorganic components, at first, we prepared the inorganic oxide mixture by the conventional frit manufacturing process; the mixture was homogenized in a water suspension, dried and melted at temperature between 1000 and 1200°C. Then the glass was quenched in air or poured in water; after it was milled and sieved at 325 mesh (< 40 μm). The powder was added to the sol-gel acid mixture (hydrolysis step) prepared from tetralkylalkoxysilanes, and applied on the cast iron surface by dipping, spraying or spreading with a blade. The cast iron surface was prepared by alternate washings with acids and bases followed by drying. To improve the adhesion largely influenced by the differences between the thermal expansion properties of the substrate and the film (the CTE, linear is 13.0 μm/m-°C for the cast iron and 2-5 μm/m-°C for the ceramic film) and corrosion resistance, the surface was treated with an activating agent like fluoro-metal acid (metal = Zr, Si) before the sol-gel colloid application. Thermal treatment at temperature between 750 and 930°C were adopted and the film evolution was investigated by SEM.
The frits were characterized by XRD analysis checking the influence of annealing temperature on the film structure and the phase evolution was investigated, so as to obtain films with superior performance. GDOES analysis was used to characterized the film composition.
The thickness was 100-150 μm with an adhesion value measured with the ASTM 3359-02 method of about 2B-3B probably due to an high hardness characteristic. More investigation on the metal oxide mixture and film properties are in course
Hybrid film: a case analysis of the sol-gel technology for improved mechanical properties application
No full textThe paper deals with the analysis of the mechanical characteristics of hybrid coating obtained through the sol-gel synthesis starting from CH3Si(OCH3)3 and C6H5Si(OCH3)3 with colloidal silica, α-Al2O3, and HNO3 as catalyst. The experimental conditions refer to a not-optimized reaction parameters trying to obtain a greater sensibility on their variations. On the base of the kinetic reaction pathway the surface morphology, analysed by SEM, the hardness, the abrasion, the film porosity and the contact angles, are interpreted. Indeed the temperature appears a relevant parameter in the control of the surface aspect and the mechanical behaviour. The roles of the colloidal silica and of the nanometric α-Al2O3 were analysed. The results demonstrate the strong enclosing of the silica particle in the hybrid polymer network. On the contrary α-Al2O3 decreases the abrasion resistance due to the lack of chemical bonds with the network
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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